Electrochemical conversion cells, commonly referred to as fuel cells, which produce electrical energy by processing first and second reactants, e.g., through oxidation and reduction of hydrogen and oxygen. By way of illustration and not limitation, a typical polymer electrolyte fuel cell comprises a polymer membrane (e.g., a proton exchange membrane) that is positioned between a pair of catalyst layers with a pair of gas diffusion media layers outside the catalyst layers. A cathode plate and an anode plate are positioned at the outermost sides adjacent the gas diffusion media layers, and the preceding components are tightly compressed to form the cell unit.
The voltage provided by a single cell unit is typically too small for useful applications. Accordingly, a plurality of cells are typically arranged and connected consecutively in a “stack” to increase the electrical output of the electrochemical conversion assembly or fuel cell. The fuel cell stack typically uses bipolar plates between adjacent MEAs.
In the operation of conventional fuel cells, the through-plane water vapor concentration gradient on the anode side causes excessive condensation. The net water flux often does not go to the cathode side. However, the cathode is able to handle liquid water better than the anode. In addition, for optimal freeze start performance, it is desirable to reduce coolant volume within the bipolar plate.
Therefore, there is a need for a fuel cell having an improved water management.